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DNA polymerase I
In prokaryotes, removes and replaces RNA primers (also functions in excision repair of danaged DNA); 3'--> 5' exonuclease (for proofreading);
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DNA polymerase II
In prokaryotes, 3'-->5' exonuclease (for proofreading); repair?
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DNA polymerase III
In prokaryotes, int the main bacterial DNA polymerase for synthesis of the leading stand and of Okazaki fragments by extencion of RNA primers; 3'-->5' exonuclease (for proofreading)
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DNA polymerase α
in Eukaryotes, forms a complex with primase and begins DNA synthesis at 3' end of RNA primers for both leading and lagging strands;3'--> 5' exonuclease (for proofreading)
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DNA polymerase ß
In eukarytoes, for repair
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DNA polymerase γ (gamma)
replication of mitochondrial DNA; 3'-->5' exonuclease (for proofreading)
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DNA ploymerase δ
- In eukaryotes, involved in leading and lagging strand synthesis (also functions in DNA repair);
- 3'-->5' exonuclease (for proofreading)
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DNA polymerase ε
In eukaryotes, thought to be involved in leading and lagging strand synthesis( also funtions in DNA repair)
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DNA primase
in both cell types, makes RNA oligonucleotides that are used as primers for DNA synthesis
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DNA helicase
unwinds double-stranded DNA via ATP hydrolysis
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Single-stranded DNA binding protein
binds to single-stranded DNA ; stabilizes strands of unwound DNA in an extended configuration that facilitates access by other proteins
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DNA topoisomerase (type I and II)
found in both cell types, makes single-stranded cuts (type I) or double-stranded cuts (type II) in DNA; relaxes DNA supercoiling; can serve as a swivel to prevent overwinding ahead of the DNA replication fork; can seperate linked DNA circles at the end of DNA replication
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DNA ligase
found in both cell types; makes covalent bonds to join together adjacent DNA strands, including okazaki fragments in lagging-strand DNA synthesis and the new and old DNA segments in excision repair of DNA
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Initiator Proteins
In both types of cells, binds to replication of origin and initiate unwinding of the double helix
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Telomerase
using an intergral RNA molecule as a template, synthesizes DNA for extension of telemeres (sequences at ends of chromosomal DNA)
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